The present invention relates to the routing of signaling messages in a communications network, such as the public switched telephone network (PSTN), or a voice over internet protocol (VOIP) network. More particularly, the present invention relates to methods and systems for routing signaling messages associated with ported subscribers in communications network.
Local number portability (LNP) gives telephone service subscribers the ability to change local service providers without changing their directory numbers. More specifically, the generic term LNP is actually representative of three basic number porting scenarios: service provider portability which allows subscribers to change local service providers without changing their phone number; service portability, which allows subscribers to change from one type of service to another (e.g., analog to integrated services digital network (ISDN) without changing their phone numbers; and geographic portability, which allows subscribers to move from one physical location to another without changing their phone numbers.
In the current, non-LNP environment, a telephone number performs two basic functions: it identifies the customer, and it provides the network with information necessary to route a call to that customer. Local number portability solutions separate these two functions, thereby providing the means for customers to keep the same directory number when changing local service providers. By separating these two functions, LNP gives customers the flexibility to respond to pricing and service changes offered by rival carriers. Accordingly, it is anticipated that LNP will promote local-exchange competition, which in turn will benefit all customers, as has already been the case with the long-distance market. As LNP solutions are implemented, competition in the local-exchange market is expected to drive down the cost of service, encourage technological innovation, stimulate demand for telecommunications services, and boost economic growth.
A number of interim number-portability methods, such as remote call forwarding and direct inward dialing exist today. However, these methods have several disadvantages: longer call set-up times, increased potential for call blocking, continued reliance on the incumbent local exchange carrier""s (LEC""s) network, loss of feature functionality, as well as substantial on-going costs to the new local service provider. Among the more long-term LNP solution approaches currently being offered, triggered LNP technology is the most relevant to a discussion of the present invention.
Triggered LNP solutions, as indicated by the name, require that both the xe2x80x9cnewxe2x80x9d and xe2x80x9coldxe2x80x9d local service providers implement a trigger function in their respective end offices. The xe2x80x9coldxe2x80x9d service provider switch (often referred to as the donor switch) administers an LNP trigger on the ported subscriber""s directory number. When activated, this trigger causes the end office switch to formulate an LNP query that is subsequently launched into the SS7 network. This LNP query is ultimately delivered to an LNP database that contains information related to service provider associated with the dialed number. More particularly, the LNP database performs a lookup based on a portion of the called party dialed digits. A location routing number (LRN) is returned by the LNP database which identifies the end office of the service provider currently serving the called party. The LRN value is then sent back to the end office that originated the LNP query. Upon receipt of the LRN containing message, the originating end office proceeds with call setup and teardown operations using the LRN as a destination address for all subsequent messages associated with the call.
Shown in FIG. 1 is an example of a telecommunications network, generally indicated by the numeral 100, that employs a triggered LNP solution similar to that described above. Telecommunications network 100 includes an originating end office (EO) 110, a recipient terminating EO 112, a donor terminating EO 113, a tandem switching office 114, a signal transfer point (STP) 116, a service control point (SCP) based LNP database 118, a calling party 120, and a called party 122. In this example, it is assumed that called party 122 has had local phone service ported from a service provider that owns EO 113 to a service provider that owns EO 112. Consequently, it is implied that the service responsibility for called party 122 was transferred from the donor EO 113 to the recipient EO 112 at some point in the past. As such, EO 112 is now assumed to service called party 122.
As such, FIG. 1 illustrates a simplified signaling message flow sequence associated with the setup of a call from calling party 120 to called party 122. When calling party 120 goes off-hook and dials the telephone number associated with called party 122, originating EO 110 analyzes the dialed digits and recognizes that the dialed number falls within an exchange that contains ported subscribers. Consequently, the originating EO 110 formulates an LNP query message M1 and sends this query message to the STP 116. Those skilled in the art of SS7 telecommunication networks will appreciate that such LNP queries and responses are typically in the form of Transaction Capabilities Application Part (TCAP) protocol signaling messages. As the TCAP protocol is well known and widely employed in the communication networks presently contemplated, a detailed discussion of the TCAP signaling protocol is not included herein.
Returning now to the message flow shown in FIG. 1, LNP query message M1 is received by the STP 116 and subsequently routed to the SCP-LNP database node 118 as LNP query message M2. The LNP query message M2 is processed by SCP-LNP database node 118, and an LNP response message M3 is formulated and sent back to STP 116. It should be appreciated that LNP response message M3 contains a Location Routing Number (LRN) associated with the recipient EO 112, which is the EO currently servicing Called Party 122. Tandem office 114 is particularly significant from a call setup standpoint, in that a voice trunk connection through tandem 114 will ultimately be required in order to establish a voice circuit with the terminating EO 112 that is currently serving the called party 122. LNP response message M3 is received by the STP 116 and subsequently routed to the originating EO 110, as LNP response message M4. The originating EO 110 processes the LNP response message M4, and uses the LRN information contained therein to formulate and send a call setup message M5. Once again, those skilled in the art of SS7 telecommunication networks will appreciate that such call setup messages are typically of ISDN user part (ISUP) format, and as the ISUP signaling protocol is well known and widely employed in the telecommunications industry, a detailed explanation of this protocol is not provided herein. Signaling System #7, by Travis Russell, copyright 1998, McGraw-Hill Publishing, the disclosure of which is incorporated herein by reference in its entirety, provides a detailed explanation of TCAP and ISUP signaling protocols.
Returning to FIG. 1, STP 116 receives message M5 and subsequently message transfer part (MTP) routes the message to tandem office 114 as message M6. Tandem office 114 examines and processes the message and formulates a message M7. Message M7 is sent to STP 116, which in turn MTP routes the message to terminating EO 112 as message M8. Those skilled in the art of telecommunications network operations will appreciate that additional call setup and teardown messages, not shown in FIG. 1, may be necessary to administer a complete a telephone call between the calling party 120 and the called party 122. The signaling message flow shown in FIG. 1 is intended only to generally illustrate a conventional LNP translation process. As these additional signaling messages are not particularly relevant to the design and operation of the present invention, a detailed discussion of call setup and teardown procedures in an SS7 telecommunications network is not provided herein.
While the approach described above is functionally capable of providing network operators with local number portability translation service, this approach necessarily requires that an originating end office switch have the ability to trigger an LNP query and to interpret the subsequent LNP response. In practice, this means that an originating end office switch must be capable of generating and launching an LNP query message into the signaling network. As such, this also implies that an originating end office switch has the ability to receive and process LNP response messages that are generated by service nodes within the signaling network.
Therefore, what is needed is a novel system and method of routing signaling messages to ported subscribers in a communications network that is transparent to the originating end office and, as such, does not require the originating end office signaling facility to directly generate and respond to number portability related signaling messages.
According to one aspect, the present invention includes a communications network element that is capable of performing triggerless routing of signaling messages associated with calls to ported subscribers. The triggerless routing node includes a communication module capable of transmitting and receiving data packets over a network. A stop action function processes incoming data packets and subsequently directs certain packets to a number portability database manager. The number portability database manager facilitates searching of a number portability database based on called party information contained within the data packets. Routing information returned by the number portability database is incorporated into the data packets, and the modified data packets are then transmitted into the communications network. Because the routing node examines and directly modifies call setup type signaling messages, no explicit translation service trigger messages are required.
Accordingly, it is an object of the present invention to provide a triggerless number portability routing node capable of modifying the content of call setup type signaling messages associated with calls to ported subscribers, so as to include a Location Routing Number associated with the ported subscriber.
Some of the objects of the invention having been stated hereinabove, other objects will be evident as the description proceeds, when taken in connection with the accompanying drawings as best described hereinbelow.